The Philips Scene Switch: an intelligent light bulb without hardware?
25.10.2017
Translation: machine translated
Philips seems to have a monopoly on the smart light bulb market. The company has just launched the Scene Switch, a series of apparently semi-intelligent light bulbs. I took a bulb apart to see how it could be intelligent without having the corresponding hardware.
"The light from this bulb can be adjusted without any additional hardware," says Senior Editor Léonie de Montmollin, holding up Philips' Scene Switch bulb.
Smart bulbs are great. They turn on and off according to predefined cycles, dim their light at specific times and much more. But they're more complicated to operate than the traditional switches we've been used to for ages. Smart bulbs require us to always have our smartphone to hand.
According to Léonie, the Scene Switches work without any additional hardware or settings. They can switch from full brightness to 40%, then 10%. What's more, they remember the brightness level at which they were last switched off.
My first instinct was to wonder how this was possible.
Let's do some research...
What Scene Switch does
The Scene Switch has one key feature: its light dims by degrees. It can also be switched on and off using a switch. The process is divided into predefined sequences:
- On: 100% brightness
- Turn off then back on: 40% brightness, light gains warmth
- Turn off then back on: 10% brightness, light gains warmth
- Turn off then on again: 100% brightness, the light loses heat and the cycle starts again from the beginning
When the Scene Switch is turned off for more than six seconds and then turned back on, it glows at the last brightness level activated.
In my opinion, it contains a board that stores the settings and probably also manages the brightness cycle of the LED light body.
The only way to check is to dismantle the bulb.
How to dismantle a bulb
Bulbs used to be simple objects: the current passed through a metal wire which, as it heated up, began to glow. There you go.
But the Scene Switch is clearly different. Léonie and I assembled our equipment, went to Dynamo's public workshop (in German), and tackled our futuristic light bulb. Come to think of it, we chose the wrong bulb. If I'd been able to see what was inside, I'd have been much more careful.
The bulb isn't made of glass
Léonie grabs my camera - a gorgeous eSony a7s II with 24-70mm lens - and I grab a glazier's diamond. I put on a pair of Carhartt work trousers that I found in our offices. If I end up covered in shards of glass, I'd rather they didn't get embedded in the jeans I'll have to wear for the rest of the day.
.
The idea is simple: split the glass, heat it with a hot air gun and plunge it into water so that it shatters where it was split. Easy, isn't it?
So I set about cracking the bulb, then go and get a tub of water and a hot air gun. Something very strange happens when I heat up the bulb: the glass deforms, although this is not the typical reaction of heat-treated glass. Instead, it tends to shine.
"Léonie, I don't think it's glass."
"It's quite possible that it's a type of plastic," she replies, taking the cooled bulb from my hands and tapping it with her fingernail. It sounds like glass, and it looks like glass too.
Very well, the bulb is surely made of plastic and so should be relatively easy to cut up without it shattering. I realise I have no idea what I'm doing. But what's the worst that can happen? I ignore the bad tongues in the editorial office who always talk to me about protection when I'm using big tools and grab a Dremel that was lying around.
Since the bulb seems to be made of some kind of plastic, I should be able to work on it with a sanding head without any problems, and without damaging the components inside. I'd like to keep the mechanism intact for as long as possible, otherwise my experiment will have been for nothing. Debris starts flying everywhere.
We put on goggles, just in case. They may make us look silly, but it's better to look silly than end up blind.
We're wearing goggles, just in case.
The Dremel starts up. Slightly nervous, I approach the plastic bulb. On first contact, I notice that I had nothing to worry about. It cuts into the material without any problem, which eventually melts under the effect of the frictional heat. In a few minutes, it's done. The ampoule lay on the work table. I've got the rest in my hands.
A first look inside the bulb
I'm surprised at first. A conventional bulb has a cable coiled around its centre, rather like the image below.
This bulb has no cables, wires or protruding parts. All the LEDs are mounted on a plate. The bulb is actually just empty space, which allows it to distribute the light well and look better than an ordinary bulb.
No turntable, or similar element that would denote any form of intelligence. The plate really just has LEDs on it. We examine it and try unsuccessfully to separate it from the socket using a screwdriver. I grab the Dremel again, but the operation proves just as difficult.
"Try it with a Flex," says Gunar Hambrecht, from Dynamo, who is watching us with interest. Generally, people come to the workshop to build something. I go there to take everything apart.
Let's bring out the heavy artillery
The situation is getting tricky. The Flex - or "angle grinder" in specialist jargon - is a very powerful tool intended more for rough work. Even with a 1mm cutting disc, it seems too big for the bulb, which is still working. I still don't want to damage the mechanism.
But Gunar is right: the Dremel isn't much help any more. I'm wondering again what risks I'm exposing myself to, but there's not much else I can do, because I need to get to the turntable in a relatively reasonable amount of time. And to do that, I need to pull out the heavy artillery.
I keep telling myself that I have a good chance of getting everything right without any problems. How wide can this turntable be? A few millimetres? Of the 360 degrees, I need to spare 45 so I don't break it. The LED plate won't survive, because it's glued.
The turntable! At last!
Thankfully, I operated carefully and narrowly avoided the turntable. The bulb will never shine again, and the disassembly is drawing to a close. The PCB appears in front of me. It's still attached by a cable to the contact surface (which supplies it with power), but I yank the cable away. The plastic part and the contact land in the bucket. I finally see what technology the bulb is packing.
The Scene Switch has given me all its secrets. I don't need to check the code; one look at the green plastic plate, coloured resistors and capacitors tells me how it works. Mission accomplished.
The current that makes the LEDs glow is carried using a copper coil that I've slightly sawed off and which also powers the computer . The green board is a sort of miniature motherboard; the capacitors and small chips certainly register the three output values: 100, 40 and 10. They can also count from 0 to 5, which explains the six-second mechanism.
In fact, the structure of the Scene Switch is simple.
- The round bulb distributes the light
- The flat LEDs provide the light
- The board stores settings and has a small battery that charges the memory
This technique is simple, but very interesting. In these days when high-tech seems to be favoured, simple technology can be just as surprising and arouse curiosity... that only a Flex will be able to satisfy. And I have to admit, I had a lot of fun.
Journalist. Author. Hacker. A storyteller searching for boundaries, secrets and taboos – putting the world to paper. Not because I can but because I can’t not.
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